Aircraft brakes typically include a plurality of stator discs and rotor discs which are compressed together during the braking operation of an aircraft. The stator discs and rotor discs are normally arranged in alternating fashion in order to form a brake disc stack
The stationary, stator discs of the disc stack are arranged in a non-rotating position surrounding an aircraft wheel or shaft. The rotating, rotor discs are secured to an outer periphery of the aircraft wheel or shaft and are normally free to rotate with the aircraft wheel when the brake is not in use.
A brake housing may include a plurality of pressure piston actuators that are arranged to provide the compressive, braking force that forces the stator discs and rotor discs of the aircraft brake's disc stack together. Brake adjustors may be employed within the brake to provide adjustment of the relative positions of the brake discs as these frictional components become worn during brake usage.
Carbon brake discs for the aforementioned aircraft braking systems are well known in the background art. Carbon brake discs offer substantial advantages relating to thermal properties and wear over other brake discs of the background art. The carbon—carbon composite materials are expected to perform at least three different functions in an aircraft brake: structural, frictional and heat absorption, e.g. serve as a heat sink. However, it is difficult to simultaneously optimize all three requirements.
U.S. Pat. Nos. 3,712,427 and 3,800,392 describe refurbishable, carbon and/or graphite brake discs having removable wear face plates. As carbon or graphite brake discs become damaged or worn, the entire assembly of brake discs may have to be replaced in order to ensure the structural integrity of the brake system and/or to maintain the original dimensions of the brake stack.
The brake discs may be machined to incorporate an annular core plate with relatively thin wear plates of carbon based friction materials forming the frictional contact surfaces of the core plates. These wear plates are either bonded or mechanically secured to the annular core plates through well-known means such as rivets, or screws. Accordingly, these types of removable wear faces offer cheaper alternative methods to refurbish and repair brake disc wear faces.
U.S. Pat. Nos. 5,558,186 and 5,779,006 to Hyde et al., describe friction discs having renewable wear faces for facilitating cost effective, refurbishment and replacement of stator and rotor discs. These friction disc assemblies include an annular structural carrier including a plurality of recessed regions having walls and torque drive notches spaced around the circumference of the carrier.
A friction lining having a flat wear face and a obverse face including raised areas for matingly engaging the walls of recessed regions of the carrier is also provided in the disc assembly. Hyde et al. describe that the depth of the recessed regions may even be less than the corresponding height of the raised areas of the friction lining. For example, FIG. 4 and FIG. 5 of U.S. Pat. No. 5,558,186 show a carrier including a plurality of recessed regions in the form of windows devoid of any material.
However, as seen in these aforementioned examples of the background art, the desired transfer of forces between the friction lining and carrier can require complex manufacturing steps. For instance, the corresponding, mating components of the brake disc assemblies may necessitate several machining steps to create the radial, circumferential and tangentially oriented components that form the assembly.
Therefore, there is a need for a simple, aircraft brake disc assembly with separate friction and core parts where the torque is transferred directly from the friction component to the core. That way the core could be optimized for strength and the friction parts can be optimized for friction/wear performance.